Thermo-switch for temperature control

ABSTRACT

A thermo-switch using the thermol expansion of a wax for closing the switch has a snapping structure for providing an abrupt closing and opening of the switch increasing the wear of the switch contacts.

United States Patent ()nishi May 22, 1973 [541 THERMO-SWITCH FOR References Cited TEMPERATURE CONTROL UNITED STATES PATENTS [76] Yukio 1,652,143 12/1927 Hart ..337/382 Nakasam Klyose (31W, 1,890,909 12/1932 Lincoln ..337/393 Japan 2,799,750 7 1957 Kovach ..337/320 [22] Filed: June 26, 1972 3,194,927 7/1965 Place ..337/388 [21] Appl. No.: 266,379 Primary Examiner--Harold Broome Attorney-Linton & Linton [52] US. Cl ..337/382, 337/388 57 ABSTRACT [51] Int. Cl. ..H0lh 37/46 1 [58] Field of Search ..337/382, 388, 389, A wswimh usi g the thermol expansion of a wax for closing the switch has a snapping structure for providing an abrupt closing and opening of the switch increasing the wear of the switch contacts.

6 Claims, 6 Drawing Figures Patented May 22, 1973 2 Sho ots-Sheet 2 OFF THERMO-SWITCH FOR TEMPERATURE CONTROL This invention relates to the structure of a thermoswitch which can be used as a switch for the cooling fan in various kinds of internal combustion engines or a temperature control device in such kinds of apparatus.

Firstly, this thermo-switch will be described with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of a thermoswitch according to the invention;

FIGS. 2 and 3 are sectional views of essential parts of this thermo-switch with FIG. 2 showing the switch at an OFF position, and FIG. 3 the switch at an ON position;

FIG. 4 is a sectional view of the snap plate in the position corresponding to FIG. 2;

FIG. 5 is a sectional view of the snap plate in the position corresponding to FIG. 3; and

FIG. 6 is a diagram showing the switching of the snap plate in relation with the lift.

A detailed description of the thermo-switch is as follows.

The thermo-switch has a spring holder 6 presenting a recess on the lower surface thereof, encapping the piston 5 installed on the wax holding element 1, a spring 7 installed around the outer lateral surface of said spring holder 6, a pushing spring 9 mounted on the top of said spring holder 6, a protruding piece 10 provided with a protruding tip 11 and set above the pushing spring 9.

A supporting frame 12 is inserted inside, on the internal surface of the outer cylinder 19 which confines the said parts, holding the snap plate 13 around its circumferential surface. The protruding piece 10 is pressed in, through the central hole of the snap plate from under by the pushing spring 9.

A swinging plate 14 working by elasticity is installed just in front of the protruding tip 11, setting the electric circuit, with its terminals 17 and 18 ON and OFF, by swinging back and forth.

The contact 15 fixed on the swinging plate 14 and the fixed contact 16 of the terminal 17 are so installed that they can be connected or separated easily under the action of the swinging plate 14. An insulating coating 20 is applied over the lateral surface of the abovementioned terminals 17 and 18 to insulate them from each other.

In the FIGS. 2 is the wax filled inside the holding element 1, 3 the diaphragm, 4 the rubber piston-head inserted under the piston, 5a the cylinder in which the piston moves back and forth, 8 the lock-washer used to keep the spring 7 from jumping up, 11a the screw groove used to adjust the protruding tip 11 slightly back or forth, 14a the stop which blocks the swinging plate at the right place when said plate swings back, and 21 the screw threads destined to fix this thermoswitch to an apparatus.

Thus the structure provided by this invention, being as described above, making use of the thermal expansion of the wax 2 filled inside the wax holding element 1 to activate the piston 5, is identical to a conventional thermostat.

This invention, however, provides a spring holder 6 encapping the piston 5 and a snapping structure comprising a pushing spring 9 and a snap plate 13.

The spring 7, being held fixed at one end by the lockwasher 8, will be compressed when the piston 5 expands up. It will press the piston down by elasticity when the temperature around the element decreases resulting in the contraction of the wax.

The protruding piece 10 is installed with the pushing spring 9 inserted on the top of the spring holder 6 encapping the piston upper surface. The insulated protruding tip 11 is set in protrusion at the center of the said protruding piece. It can be adjusted back and forth by turning the screw in the groove 11a provided on its lower end. This is destined to adjust correctly the pressure of the protruding tip 11 on the swinging plate 14.

The above-mentioned protruding piece 10 is inserted in the hole at the center of the snap plate 13 which has the shape of a rather shallow saucer, this being supported circumferentially by the supporting frame 12 and held firmly on the internal surface of the outer cylinder 19.

When the snap plate 13 is not pressed up by the piston 5, namely when the contacts 15 and 16 are separated, the snap plate is as in FIG. 4. When the spring holder 6 is forced up strongly, the snap plate 13 reverses at once and abruptly to the opposite state as shown in FIG. 5.

By this inversion the protruding tip 11 presses the swinging plate 14 up, connecting the contacts 15 and 16, closing the electric circuit between the two terminals 17 and 18, starting the revolution of the motor in case of a cooling fan.

The snap plate 13 is compressed gradually to a certain limit by the pushing spring 9 until a critical limit is reached, beyond which it reverses itself at once, abruptly.

Namely, the X coordinate in the diagram represents the lift of the snap plate and the Y coordinates the compression force. The lift by the piston 5 increases with increasing temperature, then the snap plate reverses itself at a determined point, abruptly, forcing the switch ON. When the temperature decreases, the snap plate reverses back abruptly swinging the circuit OFF.

This invention is characterized by the fact that the displacement of the piston 5 has absolutely no effect on the switch until the pushing spring is compressed to a determined extent, thanks to an appropriate combination of the snap plate 13 and the pushing spring 9.

If a snap plate and a pushing spring are not employed, and the contact of the switch is realized simply by the expansion and the contraction of the piston, the swinging plate 14 will be forced up gradually, and chattering of the contact is caused by fluctuation of the contact pressure and by vibrations, increasing the wear of the contacts.

Thus, this invention provides a highly valuable temperature switch, by storing the compression of the piston in the pushing spring 9, as described hereinabove, reversing back and forth the snap plate at once and abruptly, while making it possible to switch ON and OFF the currents of large intensity. Moreover, the use of the wax element does not cause any temperature difference due to the variation of the internal pressure under the influence of the temperature of the surroundings when the upper surface of the switch has to be sealed tightly for water-proofing.

I claim:

1. A thermo-switch for temperature control comprising a cylinder, a spring holder slideably mounted in said cylinder, a piston being encapped by said spring holder, a wax containing holder being connected to said cylinder, means positioned between said wax and said piston for transferring motion therebetween, a spring seated on the exterior of said spring holder, means retaining said spring on said holder, a second spring seated on the top of said spring holder, a snap plate mounted in said cylinder above said second spring, a protruding piece mounted on said second spring and against said snap plate, an insulating protruding tip carried by said protruding piece and extending through said snap plate, a supporting frame fixedly mounted in said cylinder and retaining said snap plate in position, a pair of terminals extending from said cylinder, a swinging plate connected to one of said terminals and positioned in front of said protruding tip, a contact on said swinging plate, a second contact on the other of said terminals positioned for being engaged by said first contact, an insulating coating being positioned for insulating said terminals from one another.

2. A thermo-switch as claimed in claim 1 including a second cylinder connected to an end of said first cylinder and having said wax holder connected to and closing said second cylinder, said piston being slideably mounted in said second cylinder and said terminal extending from the other end of said first cylinder.

3. A thermo-switch as claimed in claim 1 wherein said cylinder has a stepped bore, said spring holder has a flange normally seated on a step of said bore and said first spring seated on said flange and a washer is fixedly mounted in said bore above said spring holder, has said first spring seated thereagainst tending to hold said spring holder seated on said bore step and said second spring extends through said washer.

4. A thermo-switch as claimed in claim 1 wherein said protruding tip is adjustably mounted on said protruding member.

5. A thermo-switch as claimed in claim 3 including a supporting frame fixedly mounted in said cylinder bore above said snap plate and said snap plate has its rim portion seated on a second step of said cylinder bore and retained thereon by said supporting frame with said protruding tip extending axially of said cylinder bore.

6. A thermo-switch as claimed in claim 5 wherein said snap plate is of an annular shallow cup configuration and of a resilient material. 

1. A thermo-switch for temperature control comprising a cylinder, a spring holder slideably mounted in said cylinder, a piston being encapped by said spring holder, a wax containing holder being connected to said cylinder, means positioned between said wax and said piston for transferring motion therebetween, a spring seated on the exterior of said spring holder, means retaining said spring on said holder, a second spring seated on the top of said spring holder, a snap plate mounted in said cylinder above said second spring, a protruding piece mounted on said second spring and against said snap plate, an insulating protruding tip carried by said protruding piece and extending through said snap plate, a supporting frame fixedly mounted in said cylinder and retaining said snap plate in position, a pair of terminals extending from said cylinder, a swinging plate connected to one of said terminals and positioned in front of said protruding tip, a contact on said swinging plate, a seCond contact on the other of said terminals positioned for being engaged by said first contact, an insulating coating being positioned for insulating said terminals from one another.
 2. A thermo-switch as claimed in claim 1 including a second cylinder connected to an end of said first cylinder and having said wax holder connected to and closing said second cylinder, said piston being slideably mounted in said second cylinder and said terminal extending from the other end of said first cylinder.
 3. A thermo-switch as claimed in claim 1 wherein said cylinder has a stepped bore, said spring holder has a flange normally seated on a step of said bore and said first spring seated on said flange and a washer is fixedly mounted in said bore above said spring holder, has said first spring seated thereagainst tending to hold said spring holder seated on said bore step and said second spring extends through said washer.
 4. A thermo-switch as claimed in claim 1 wherein said protruding tip is adjustably mounted on said protruding member.
 5. A thermo-switch as claimed in claim 3 including a supporting frame fixedly mounted in said cylinder bore above said snap plate and said snap plate has its rim portion seated on a second step of said cylinder bore and retained thereon by said supporting frame with said protruding tip extending axially of said cylinder bore.
 6. A thermo-switch as claimed in claim 5 wherein said snap plate is of an annular shallow cup configuration and of a resilient material. 